1. Field of the Invention
The present invention relates to a self-heating, self-indicating cosmetic composition which gives users indications of the length of time of application, location of effective application and the degrees of mixing and scrubbing when in use.
2. Description of the Background Art
Facial masks are products which are designed to provide a different type of cleansing effect than that which can be achieved with ordinary cleansing compositions. In this context, an ordinary cleansing composition is one which consists primarily of surfactants and emollients delivered from an aqueous vehicle. Ordinary cleansers remove dirt and soils, especially oily soils, by two primary mechanisms. The first, which is typical for foaming cleansers, including bar soaps, cleans the skin by a detergent effect obtained by the use of surfactants. The second mechanism, which is typical for non-foaming cleansers such as "cold cream", depends on a solvent effect whereby various emollients in the composition dissolve and lift up soils from the skin. Such compositions, together with the suspended soils are then removed by wiping the composition off with a tissue, or by similar means.
Facial masks can be classified as being of two general types. The first type is a "peel-off" mask which consists of a polymer, typically polyvinyl alcohol, in an aqueous or hydroalcoholic solution. These compositions are applied to the skin and allowed to dry. As the water and/or alcohol dries, the polymer forms a film which adheres to the surface of the skin. This film is then peeled off the skin, removing top layers of the skin together with any dirt of soil which may be present on the skin surface. The second type of mask is the "rinse-off" type. Rinse-off masks typically contain some type of finely-divided particles which are able, presumably due to their large surface area, to adsorb oily soils, particularly sebum. The most common type of powders used in rinse-off masks are clays, and the clays are typically suspended in an aqueous vehicle. The composition is applied to the skin and allowed to dry. Then the dried "cake", together with the adsorbed oil is removed from the skin by rinsing.
A problem observed with moisturizing compositions is that many components typically found in a moisturizing composition are a solid at or near room temperature, which can present difficulties in terms of penetration and distribution. Moisturizing compositions are generally formulated as an aqueous emulsion, however, a problem with emulsion delivery systems is that the presence of large amounts of water decreases the effectiveness of delivery of the moisturizing components. Pre-heating of the composition to provide a hot facial moisturizer may be conducted by conventional heat transfer methods, however such a heating is not always convenient and significantly complicates the moisturizing process.
In order to formulate a personal care composition which is "self-warming", the combination of an activated zeolite and anhydrous liquid vehicle has been reported (U.S. Pat. No. 4,626,550). The addition of a "self-warming" component to a rinse off cleansing mask composition provides for more effective sebum removal and an improved sensation during use. However, some self-warming zeolite materials provide for a composition of high alkalinity (as high as pH 12), such that it is desirable to minimize exposure time with the skin. A contact time ranging from 1-2 minutes is preferable. However in use, it is not always convenient to accurately measure time such that over exposure is a concern. In addition, the user of a cleansing composition may over scrub or under scrub (e.g. no scrubbing), such that irritation and/or sub-optimum cleansing may occur.
Moreover, when using an anhydrous "self-warming" component, which liberates heat of hydration, the quality of the warming will in-part, depend on the effectiveness of mixing of the anhydrous "self-warming" component with water. If the water and anhydrous "self-warming" components are not thoroughly mixed, the rate and degree of hydration may be reduced, and therefore, both the rate of heating and temperature rise will be sub-optimal. However, when using cleansing and/or moisturizing compositions, it is very easy to leave regions in which ineffective mixing occurs, since it can be difficult for the user to identify regions which have been thoroughly mixed. Effective mixing when using a "self-warming" component is thus desirable.
Accordingly, a self-warming cosmetic composition which, in use, provides an indication of time of use, effective application, as well as degree of mixing and scrubbing, would be an improvement over existing technology.